After the second APVR measurement the pressure needed to reach 4 liter is calculated and the insufflator is set to this value with a maximum of 15 mmHg in every patient. If during the second APVR the patient presses or breathes against the ventilator this will be noted as a failure to measure the APVR. A dose of rocuronium 1 mg/kg IBW is given followed by an infusion to keep PTC < 4.